


Fishtail

by siqwithaQ



Category: One Piece
Genre: Alternate Universe - Merpeople, Gen, Plot Twists, Way Too Many Plot Twists
Language: English
Status: In-Progress
Published: 2014-10-14
Updated: 2014-10-14
Packaged: 2018-02-21 03:26:23
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 4,828
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2452973
Author URL: https://archiveofourown.org/users/siqwithaQ/pseuds/siqwithaQ
Summary: <blockquote class="userstuff">
              <p>By chance, Usopp happens upon a merman named Luffy, not only opening his eyes to creatures beyond humans, but giving him the inspiration he needed for an important art project. Soon, his classmate Ace also takes an interest in the merman — now, if only they could get Luffy to talk to them!</p>
            </blockquote>





	1. First Encounter

**Author's Note:**

> So, transferring the first eight chapters of this story over to here. Don't expect rapid updates after that — the first eight chapters were written over the course of two years!

Usopp took a deep breath before walking into the final chamber of the underground cave. It seemed that had been the right idea, as the sight that met him was breathtaking.

The artist had stumbled upon the entrance to this cave earlier that day. He had been searching for something to draw and thought the place was so disturbingly perfect he just had to. He could tell, though, that the cavern would be even more spectacular after dark, and therefore resolved to return later with every piece of art equipment he could carry. He mentally gave himself a pat on the back as his eyes scoured the area. His find was truly incredible.

Odd, greenish crystals glittered on the walls, and the walls themselves contained a silvery tint that hadn't been noticeable during the daylight. The stalactites above Usopp's head created more of a chandelier-like effect than anything else, and the glossy floor shone as if it had just been polished. Last but not least, there was a mid-sized pool in the centre of the chamber floor. The waters shimmered in the starlight, and if you looked into them you wouldn't be able to tell how deep it went. It was saltwater, Usopp had tested, which meant the inlet was probably connected to the ocean somehow. Usopp could deduce from this that the cave he was in now was probably far, far underground. He had actually lost track of time on his way through the downwards tunnel to get there, so it must not have been that much of a stretch to assume so.

Usopp settled himself down near the wall and reached for his sketchbook. There was only one problem left unsolved as he flipped for an empty page.

What to draw?

Should he draw the cave as a whole? Or maybe a design of the crystals on the wall, or a single crystal apart from the others, or even the stalactites? He could draw the water and practice making light refract in  _just_  the right way–

A loud splash snapped Usopp from his reverie.

He dragged his eyes over to the waters — the very waters he'd just been contemplating — and saw a black haired boy, no older than him, had just surfaced from underwater.

The boy had his back to him, but Usopp could tell he was smiling despite that. The previously swimming teen was practically radiating joy. Usopp could feel himself being uplifted from the second-hand exuberance, and the room seemed to glow just the tiniest bit more than it had a second ago. He was still examining the boy when something bizarre happened. The boy leaned forward, away from Usopp, when a large fish's tail fin popped up out of the water.

It was most definitely large indeed. By size alone it could have possibly been a shark's or a dolphin's. Otherwise, it was something that could only belong to some kind of tropical fish. It was almost translucently white in colour, and flowed outwards beautifully, not unlike a bride's veil.

Shocked at the revelation, as it looked like the tail was connected to the boy, Usopp couldn't stop a whispered question from passing his lips.

"What… What  _are_  you?"

The mermaid — Merman? — gasped and spun around to see him. Usopp got a half-second long look at panicked brown eyes before the boy — and his tail — disappeared unto the water.

The human crawled on his hands and knees to the pool and peeked down. There was the boy, looking up at him from only a hair's breadth beneath the water's surface, meeting his gaze with just as much curiosity, if not more. From this close, the boy's wide brown eyes, a scar beneath one of them, were made more visible. Usopp took one glance at the other's youthful features and decided merman was not the right term for someone like him. He thought 'mer-boy' was much more fitting.

He reached out to let his fingers graze the top of the water, but the mer-boy quickly turned and dived downwards, stopping after a second. The mer-boy was much further down than he originally was, looking almost doll-sized to Usopp, but somehow could still be seen clearly, as if he really did radiate joy in the form of light. From this distance, Usopp could finally make out how extensive the boy's tail actually was. The tail must have been at least three — no,  _four_  times as long as Usopp was tall. It almost looked like it was made of pure white ribbon as it danced and coiled around the boy in the water. The sight was ethereal.

The mer-boy took one last look at Usopp before, with a flick of his lengthy tail, he sped away.

Usopp lingered near the water for a moment, but went back to his sketchbook. The image of what happened just a minute ago would be burned in his mind forever, but he was glad for it.

He may not have gotten to actually talk to the mer-boy, but that didn't matter.

He had a great idea for his next art project.


	2. Distracted Chats

**Notes for the Chapter:**

> I honestly am not fond of how angsty this chapter begins, but eh, what can you do?

All scenery was a blur before his eyes as he sped away, his body gliding easily through the sea. It had always been a talent of his to swim swifter than even the fastest of the fast, probably aided by his atypically long tail.

When he could tell he was getting closer to his destination, he finally slowed himself to a more leisurely pace. He wrinkled his nose absently as he weaved through bits of floating trash in the water, his mind still hovering around the encounter he had earlier.

_That was a human. A human! Wow. I met a human. I met a human. I met a human!_

He secretively covered the grin that the thought had brought on with his hands. Having just arrived at the border of the underwater village he called home, the outcast knew that it would be a bad idea to let other villagers see him so giddy. He knew if they did, it would get back to his main antagonists through word-of-mouth, and he would be in for trouble.

_Do all humans have noses that long? Or is he… Is he like me?_

He had always been victimized, for as long as he can remember, because of his  _anomaly_. His  _unnaturalness_.

They  _hated_  him for his  _freakish_  tail.

After all, it took up so much space that it was always in the way. What good came of a tail that was triple or more a human's height in length? It was onlya burden that did nothing more than attract some petty, unwanted attention.

Did that human have the same troubles? Was he bullied and snubbed by his peers for his long nose?

Maybe all humans  _did_  have long noses.  _Maybe he was staring at me like that because my nose was short and weird to him._

Wonderful. Another thing to put in the gap between the  _him_  and the  _normal_.

It hit him very suddenly that he had been floating in the middle of the pathway, obstructing people from passing easily, when he was pushed harshly out of the way and out of his thoughts.

"Move it, Freaktail."

_Freak_

_Freak Freak Freak Freak Freak Freak Freak Freak FreakFreakFreakFreakFreakFreak_

He rocketed himself away, ducking behind whatever could fit his tail. It just wouldn't do to be dragged down into this issue when he had to go see Shirahoshi. He let himself grin more openly this time as he practically teleported to the palace with his extraordinary speed, sneaking in to see his one and only friend and sympathizer.

Shirahoshi had never been truly accepted either. She was many times the size of a house, and the only reason she was any better off than him was that she was the princess of their village and people were obligated to be polite to her.

They weren't, however, obligated to be friendly.

He loved visiting Shirahoshi. Her room was always impeccably clean, in such a way he would never be able to manage himself. The furnishings were lavish, and there was even a chair large enough that he could stretch himself out end to end on it and not only fit (a rarity in itself) but have extra room. He would often bring her gifts or stories, help her do her hair or play a game with her and Megalo, and she would feed him, and all the while they would have long conversations about anything that held their interest that day.

Today, she offered him a small smile from her seat by her mirror, and he swam over to pick up her comb.

"Father still hasn't returned from his trip. Uncle has been taking care of us, but I still miss him."

He nodded his acknowledgement at her as he separated three lengths of hair for a braid, wrestling one in both arms and holding another with his tail, leaving a third hanging loose. They were disproportionate, but it was the best he was going to get so he didn't mind that.

"Sometimes, though, I think Uncle has been a little too hard on my brothers."

Carefully holding one of the lengths of hair, he slipped it in between the other two before grabbing the next and repeating the process. The only sign he heard what she said was a faint  _Hmmm?_

"Earlier, he made Fukaboshi fix up a heap of Bon Chari after he dropped his pasta on the floor. Fukaboshi doesn't even know anything about Bon Chari!"

He always found it a bit ironic that their culture imitated such human customs like cuisine and architecture while even the most minor of acquaintanceships with humans were strictly taboo.

He had almost finished up the last of the braiding.

"The worst part is he's trying to pressure me to marry."

Distracted, he merely made an aggravated noise as he tried to reach the hair tie while simultaneously holding the end of the braid. Why did it have to be sitting on the furthest possible counter from them? Her hair made a rope connecting him to her head, not letting him get as far away as he needed to. The damn thing was just beyond his fingertips. If he could only reach a little further… Ah-ha!

"But, but…" She sniffled. "I just know that no one is going to want to marry a weirdo like me!"

Behind her, there was some thrashing as he tried to stretch the hair tie to contain her newly braided hair.

"Luffy?" She simmered with confusion at his silence, only now noticing he had yet to say a word. He was usually a lot more vocal…

The boy grinned at his handiwork. Shirahoshi's hair was now done in a lopsided braid that was  _beautiful thank you very much._  He let himself go lax, hanging from her hair like a monkey on a tire swing.

"Luffy?" she asked again, turning around to see him.

Unfortunately, her quick turn meant that her new braid swung around, bringing Luffy with it. He yelped with surprise.

"Huh? Oh, I'm sorry…" she apologized, poking at him where he was squished against her breast after having been thrown over her shoulder.

"It's fine!" he finally laughed. "I should be the one saying sorry... I wasn't listening at all!"

"It's alright. I think I'd rather talk about something else anyway," she consoled.

Luffy nodded, taking another look at the braid. When he thought about it, it would look better with some kind of decoration with it. Quickly, he grabbed a piece of kelp from a plant nearby and began to thread it through her hair.

"Did anything interesting happen to you today?" she asked, honestly curious.

_Don't tell her a human saw you, don't tell her a human saw you. Just say "Nothing Much" and leave it at that. Don't tell her a human saw you, don't tell her a human saw you–_

"A human saw me today."

_Damnit!_

"What?!"

She turned her head rapidly, again swinging the braid – and Luffy. This time, the slippery kelp made him lose his grip, slamming into the wall.

"Ah! I'm so so sorry!" she cried, breaking down into soft sobs.

Luffy sighed. He wondered how in the Seven Seas he was going to explain this and convince her not to tell her Father.

 


	3. The Classmate

Usopp was glad he went to a predominantly art based college. If he told his professor that he needed to work on location for his big project, he got a pass to go for it and work away from the school for as long as he liked, so long as he kept his professor updated on his progress. He had made use of this to spend as much time as possible in the cavern.

He had never felt quite so inspired before. Already, he had filled countless sketchbooks, made numerous paintings, and even a little clay figurine. There were drawings done in pencil crayons, watercolours, poster paint, pastels, charcoal, and whatever he could get his hands on on any given day. There was even one made with children's crayons.

Some of the drawings were of the cave, but the vast majority were of the merboy he had glimpsed that day. He kept all his work in the cave itself, as there were far too many for him to carry home on his own, and he wasn't ready to show his drawings to anyone just yet. He knew they were safe there from prying eyes; the cavern was too difficult to find.

The entrance was hidden within a rock face by the odd formation around it. There was a thin sheet of rock, covering the entrance like a curtain. Besides that, the rock face itself was a challenge to reach. You had to climb up a steep mountain of a rock just the right way and then edge along a narrow protrusion just to get there, all the while the ocean below crashed onto jagged stones and invited painful death to those who fell.

If that didn't deter you, there were multiple paths to take once you had gotten past the entrance. All of them were only just large enough for an adult to fit through, and Usopp would have had a tough time if he were any bigger than he was. Only a single pathway would take you to the right cavern, and that pathway continuously split off into multiple branches. It would have been impossible to navigate, considering the darkness within the rock was all-consuming, but Usopp had painted small, glow in the dark arrows to help him.

And so he kept his artwork there, where no one could ever see them. Except one person.

In part of his mind, Usopp was hoping for the merboy to come back, to see the drawings he'd made. He wanted to know what the merboy thought, if he liked them, if he was even okay with this all. He was starting to believe that he would never know, but part of him still desperately wanted to. Another part of him desperately wanted that annoying beeping sound to stop.

Wait, what?

There was a loud beeping noise broadcasting from his pocket. Digging his fingers through it came up with a cell phone, loudly informing him that he had a message.

' _shithead get ur ass over here. its more urgent than ur project'_

It was from his friend Sanji. If Usopp didn't go now, he would really be in for it later. The man had a temper that could only be soothed by beautiful women — a demographic that Usopp definitely did not belong to.

Sighing, he put down the simple pencil sketch he had been working on. Feeling his way up through the passage, he used the arrows to guide himself rather than the flashlight in his pocket, as usual. He slid through the curtain of rock in front of the entrance and tiptoed carefully down the slender ledge. He clambered down the rock face measuredly, only to jump down the last distance to the ground and land in front of someone.

"GYAAAH!" he yelled as soon as he realised he was facing a stranger, receiving a similar exclamation of shock in return. It wasn't long before they both had their flashlights shining in each other's faces. Usopp paled when he registered whom he was looking at. "P-Portgas-senpai!" he stuttered. "What are you doing here?"

Standing in front of him was the most well-known student at his school, his upperclassman Portgas D Ace. Ace was admired by most of the school for his good grades, good looks, and good-natured personality. He had won multiple local art competitions already at his age, put up against older competitors who had more training and experience than himself. He had a bustling social life and hell, he practically had an army of fangirls!

So, it was  _just a little_  daunting for bottom-of-the-social-latter Usopp to be meeting him.

Ace gestured to the objects (were those sticks?) he was carrying under his arm. "I'm collecting driftwood for a project." (Yes, they were sticks.) "What are  _you_  doing here?"

"I am also doing a project," Usopp answered mechanically, and Ace raised an eyebrow at him.

"Alright then." Damnit. He just made himself look like an ass, didn't he? "But where's your stuff?"

"I-i-it's… somewhere else!" He was panicking now and he didn't know why. "I've g-got to go!"

And he ran.

* * *

 

Ace watched the long-nosed boy as he ran off. Fuck. Why were the kohai always so scared of him? When the boy rounded a corner and out of sight, Ace glanced around himself and wondered where the kid had come from. It had sounded like he had dropped onto the ground from some height, but where?

He stood in front of a steep rock face with the sea behind him. To his left, the sand dropped away suddenly and waves battered upon rough stones. The rock face was smooth as if it had been polished, except for a few indentations—

No, hang on. Indentations. Indentations in a smooth, steep rock face, just big enough for a hand. He trailed the beam from his flashlight up the linear trail of notches as something ached in the back of his memories. The light fell on a thin ledge, which led halfway down the wall-like stone towards a…

_The rock face looked especially dull that day as eager hands brought the chisel to it._

He could almost remember something. Something important.

 _The rock face was featureless. It wouldn't be for long_.

He remembered… He remembered…

_Footsteps along an thin ledge. An overpowering feeling of triumph._

He remembered.

_The cave._

Placing his flashlight between his teeth, he began to scale the wall using the notches carved out so many years before.

Slinking down the ledge and through the pathway was harder than he remembered, though it was probably because he was a lot bigger than he used to be. Even if he hadn't seen the arrows, he would still have been able to find the cave with his eyes closed. He had taken this route so many times before the directions were seared into his being.

And there it was. The cave. The very same cave he had claimed for himself in his childhood, the one he had spent months trying to reach, the one he hadn't revisited for years and years and had nearly forgotten was still there. Still here. And… covered in drawings?

There was paper everywhere, all covered in art and paint and colour, littering the ground like breadcrumbs. Ace picked one up off the floor to take a good look at it, observing briefly that each piece was of the same thing, with a couple exceptions. And what a picture it was.

It was a watercolour painting, marvellously created. It showed a lot of promising talent, though that wasn't what Ace focused on.

The picture itself was of a boy. A boy with black hair, a scar, and a smile. It showed him from an aerial view; he was looking up at the viewer of the painting. The boy was underwater, that much was obvious, and he was grinning cheekily.

And he had a tail.

An honest, immense fish tail trailing down behind him.

Ace looked at the other pictures, all of the same boy, and noticed that some poses were drawn more than others. Most common were drawings of the boy a hair's breadth away, looking up curiously at his viewer. The water's surface rippled his appearance oh-so-slightly. Second were portrayals of the boy farther down and doll-sized, his tail capering around him, beautiful and flowing like silk. Third were depictions of him leaning forward against the edge a pool, back to the viewer, and proudly displaying his shroud-like tail. That pool — the same pool as was in that very cave _._  He could recognise it anywhere. The third were the only drawings of him above water.

After having seen those three poses, all the rest suddenly looked the slightest bit off, like they were experiments, like they were drawn without reference. The pictures varied in medium; there were multiples of each of the three poses, all created with different tools, and the other poses varied just as much, but they were all of him. All of the same boy, with the same face, the same scar, and the same tail.

Ace could tell from the make of the art. From the details, the style, the perspective, the repetition, the flaws and the flawlessness. Ace could tell.

It was real.

It was very real.

And the long-nosed boy had seen it.


	4. His Brother

"If your shitty dog was going to hide from me, where would it be?"

Usopp stared at Sanji incredulously. "You lost Chopper. You lost him, didn't you?"

"No!" Sanji objected vehemently. "I just… don't know where it is."

Usopp rubbed his temples and sank onto the leather couch. "Okay, tell me what happened."

"So I came to your shitty house—" a broad gesture to the living room around them, "—to feed it like you asked me to, and I swear your dog speaks human, because when I made a joke about cooking  _it_  for dinner, it ran away and hid."

He gaped. "You said you were going to  _eat him?_ "

"I was joking!"

"Okay, okay!" He threw up his hands. "Whatever. Let's just find him before he pisses on something important. He still isn't house broken, you know."

* * *

Luffy watched the arriving Yagara curiously.

He had been napping far outside the city limits when he first saw it approach. It was carriage-like in appearance, decorated with purple, gold — which he knew were royal colours — and for some reason, sea foam green. It was pulled through the water by two large fish, making Luffy wonder who was inside.

_What merperson doesn't want to swim?_

He'd tailed the Yagara on its way just to satisfy his curiosity. They were still a long distance from the city and the Yagara was going very slowly — compared to what Luffy was capable of — so he was in no real rush, but he  _was_  impatient. So, cautiously, he swam up to its side and peeked through a window.

He was met with the startlingly green eyes of a grizzled merman, whose hair looked laughably similar to moss.

He waved.

* * *

" _Finally_ ," Usopp stressed, plopping down into a kitchen chair with his Pomeranian safely in his arms. "I had to leave my project behind to help you when all you had to do was look in the closet?"

"How would I know it'd be in the closet?" Sanji asked, pulling a cigarette from his breast pocket and lighting it. For once, Usopp didn't protest. "Shit. You're so tired you're not even gonna scold me for smoking? You really have been running yourself ragged with this project. You haven't been procrastinating, have you?"

"No, no. I've just been so inspired I want to work as much as I can."

"Well, that's good," Sanji told him, "because the final presentation's in a few days, and you better be finished by then."

"Yeah, I know. I just need someone to help me move the pieces, mainly. Feel like helping? You can be the very first person to see the work I've done," Usopp offered.

Sanji smirked. "I'd be honoured."

* * *

The Yagara charged through the water, bringing its riders to their destination of Fishman City. Zoro and Kuina relaxed in the comfortable seats as Kuina slept and Zoro watched the scenery out the window.

That is, until someone's face blocked his view.

The first thing that struck him was that the boy (for it was certainly a boy) was somehow keeping up with the Yagara, despite the Yagara being the fastest mode of transportation known to merman, and they were going top speed.

The boy waved.

Zoro waved back.

The boy grinned, then took off incredibly quickly and outpaced the Yagara within a second. Zoro noticed that, even with the boy's impossible speed, it took a considerable time for his entire tail to go past.

Zoro leaned his upper body out the window, just in time to see the boy stop, turn backwards, and wave to him again. It was then, and only then, that he saw the lengthy white tail that cleaved the water like mist. Then the boy was gone.

* * *

"Hey, Sabo!"

"What is it now?" Sabo twisted in his chair, away from his work desk, and looked at his twin brother exasperatedly.

"You'll  _never_  guess what I saw today," Ace said, grinning like a maniac.

He sighed. "What?"

"There are these drawings one of the kohai—"

"It's rude to call them that, you know."

"These drawings a long-nosed boy made," Ace corrected himself. "And you know what they're of? A  _merman_."

"So? There's loads of art about mythical creatures," Sabo pointed out. "What's the big deal this time?"

"Well, this time, it's real."

"For the love of…" He put his head in his hands. "How many times are you going to have to be told that things like that aren't real?"

"I  _know_  this is real, Sabo. You just can't draw something as detailed as he did without reference."

"That doesn't mean the merman's real. It could have been drawn from a figurine or a guy in a costume," Sabo contradicted.

Ace shook his head. "I think they're—"

"Enough," Sabo cut him off, standing. "I'm not going to get any work done like this. I'm going upstairs, you believe whatever you like."

He picked up his books and papers, leaving the unimportant ones because it had taken him two trips to get them to his desk anyway, and made to ascend the nearby staircase. He might have gotten somewhere, but Ace placed himself in front of the narrow entrance to the stairs in a (successful) attempt to stop him.

"But wait! This is important!" his brother protested. "I think—"

"How is this  _important_? It's just some kid's fantasy," Sabo scoffed. "Now if you'll excuse me, I have exams to study for. Unlike you _._ "

He tried to step around him, but Ace countered. "Just listen to me, okay? Forget the merman part, the guy's still real. You said so yourself."

"I said he might be," he reminded, "but yes, the guy's still 'real,' even if he's only a figurine. What about it?"

" _What about it?_ " Ace imitated incredulously. "Do you  _know_  what he looked like?"

"How could I?" Sabo exclaimed, dropping his books back down on his desk in frustration. "I didn't see the pictures!"

"He looked like– give me that." Ace tore a piece of lined paper from between the pages of one of Sabo's book, at the same time taking an art pencil from his own pocket.

"Those are my notes," Sabo complained as Ace flipped the page over to where there was still some empty space and started on a quick sketch (to Ace anyway; as an artist, what was a rough sketch to him was a rather impressive portrait to his non-artistic brother).

"Here," Ace said, handing the drawing to Sabo when he finished. "That's him."

Sabo huffed in annoyance but took the sketch anyway. Ace didn't have an eraser with him, so he could still see the faint base lines of the face, dictating where the eyes fell. Sabo scanned the drawing once, then twice, then a third time as shock pushed the irritation off his face. He looked back at Ace, who was waiting patiently, and they shared a look of understanding. "…No."

"Yes," Ace insisted.

" _No_."

"Yes."

"Really,  _no._ "

"Really, yes." Ace took the sketch back from him gently, gazing down at that  _face_ for himself.

"But… how?"

"I don't know how and I don't know why," Ace ran his fingertips down the page gingerly, almost afraid to somehow hurt the pictured boy. He looked up pointedly at Sabo and continued, "…but they were pictures of Luffy."


End file.
